Semiconductor systems

ABSTRACT

A semiconductor system includes a controller and a semiconductor device. The controller outputs a clock signal, a chip selection signal and a command/address signal. The controller includes a controller termination circuit turned on during a read operation. The controller receives first data through an input/output (I/O) line coupled to the controller termination circuit during the read operation and outputs second data through the I/O line coupled to the controller termination circuit turned off during a write operation. The semiconductor device includes an internal termination circuit turned off during the read operation, outputs the first data through the I/O line coupled to the internal termination circuit based on the chip selection signal and the command/address signal during the read operation, and stores the second data inputted through the I/O line coupled to the internal termination circuit turned on during the write operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C 119(a) to KoreanApplication No. 10-2019-0002383, filed on Jan. 8, 2019, which isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

Embodiments of the present disclosure generally relate to semiconductorsystems performing an on-die termination operation.

2. Related Art

As a swing width of transmission signals between semiconductor devicesincluded in a fast semiconductor system is gradually reduced, reflectionof the transmission signals has severely occurred at interface stagesbetween the semiconductor devices due to impedance mismatch. Theimpedance mismatch may occur due to variation of process condition.Thus, an impedance matching circuit (also, referred to as “on-dietermination (ODT) circuit”) has been used in semiconductor systems tosuppress the reflection of the transmission signals.

SUMMARY

According to an embodiment, a semiconductor system includes a controllerand a semiconductor device. The controller configured to output a clocksignal, a chip selection signal and a command/address signal. Thecontroller includes a controller termination circuit configured toadjust a drivability of an input and output (I/O) line during a readoperation. The controller configured to receive first data through aninput/output (I/O) line coupled to the controller termination circuitduring the read operation and outputs second data through the I/O linecoupled to the controller termination circuit configured to not adjust adrivability of the I/O line during a write operation. The semiconductordevice includes an internal termination circuit configured to inhibitthe I/O line from being driven during the read operation. Thesemiconductor device configured to output the first data through the I/Oline coupled to the internal termination circuit based on the chipselection signal and the command/address signal during the readoperation. The semiconductor device configured to store the second datawhich is inputted through the I/O line coupled to the internaltermination circuit configured to adjust a drivability of the I/O lineduring the write operation.

According to an embodiment, a semiconductor system includes acontroller, a first semiconductor device and a second semiconductordevice. The controller configured to output a clock signal, first andsecond chip selection signals and a command/address signal. Thecontroller includes a controller termination circuit which is configuredto adjust a drivability of an input and output (I/O) line during a readoperation and turned off during a write operation. The firstsemiconductor device includes a first internal termination circuit whichis configured to inhibit the I/O line from being driven during the readoperation and the write operation based on the first chip selectionsignal and the command/address signal. The second semiconductor deviceincludes a second internal termination circuit which is configured toadjust a drivability of the I/O line during the read operation and thewrite operation based on the second chip selection signal and thecommand/address signal. The controller termination circuit, the firstinternal termination circuit and the second internal termination circuitshare the input/output (I/O) line with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of asemiconductor system according to an embodiment of the presentdisclosure.

FIG. 2 is a block diagram illustrating a configuration of a firstinternal input/output (I/O) circuit included in the semiconductor systemof FIG. 1.

FIG. 3 is a table illustrating various logic level combinations of achip selection signal and a command/address signal for operations of thesemiconductor system shown in FIG. 1.

FIG. 4 is a block diagram illustrating a configuration of a drivecontrol circuit included in the first internal I/O circuit of FIG. 2.

FIG. 5 is a circuit diagram illustrating a configuration of an ODTcontrol circuit included in the drive control circuit of FIG. 4.

FIG. 6 is a circuit diagram illustrating a configuration of anenablement signal generation circuit included in the drive controlcircuit of FIG. 4.

FIG. 7 is a block diagram illustrating a configuration of a controlsignal generation circuit included in the drive control circuit of FIG.4.

FIG. 8 is a block diagram illustrating a configuration of a drive signaloutput circuit included in the first internal I/O circuit of FIG. 2.

FIG. 9 is a circuit diagram illustrating a configuration of a pull-downdrive signal output circuit included in the drive signal output circuitof FIG. 8.

FIGS. 10, 11 and 12 are timing diagrams illustrating operations of asemiconductor system according to an embodiment of the presentdisclosure.

FIG. 13 is a block diagram illustrating a configuration of asemiconductor device employed in a semiconductor system according to anembodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Various embodiments of the present disclosure will be describedhereinafter with reference to the accompanying drawings. However, theembodiments described herein are for illustrative purposes only and arenot intended to limit the scope of the present disclosure.

The word “coupled,” as used herein for some embodiments, means that twocomponents are directly connected with one another. For example, a firstcomponent coupled to a second component means the first component iscontacting the second component. For other embodiments, coupledcomponents have one or more intervening components. For example, a firstcomponent is coupled to a second component when the first and secondcomponents are both in contact with a common third component even thoughthe first component is not directly contacting the second component.

As illustrated in FIG. 1, a semiconductor system 1 according to anembodiment may include a controller 10, a first semiconductor device 20and a second semiconductor device 30.

The controller 10 may output a clock signal CLK, a first chip selectionsignal CS1, a second chip selection signal CS2, and first to seventhcommand/address signals CA<1:7>. The controller 10 may output data DATAduring a write operation and may receive the data DATA during a readoperation. The controller 10 may output a data processing signal DMIduring the write operation and may receive the data processing signalDMI during the read operation. The controller 10 may output a strobesignal DQS during the write operation and may receive the strobe signalDQS during the read operation. The data DATA may be inputted to oroutputted from the first semiconductor device 20 and the secondsemiconductor device 30. The data processing signal DMI may be a signalfor performing a masking operation and a data bus inversion operation ofthe data DATA which are inputted to or outputted from the firstsemiconductor device 20 and the second semiconductor device 30. Thestrobe signal DQS may be a signal for strobing the data DATA which areinputted to or outputted from the first semiconductor device 20 and thesecond semiconductor device 30. Although the data DATA, the dataprocessing signal DMI and the strobe signal DQS are illustrated as asingle signal in FIG. 1, each of the data DATA, the data processingsignal DMI and the strobe signal DQS may be set to include a pluralityof bits in some embodiments.

The controller 10 may include an external input/output (I/O) circuit 11and a controller termination circuit (CNTODT) 12. The external I/Ocircuit 11 may output the data DATA, the data processing signal DMI andthe strobe signal DQS during the write operation. The external I/Ocircuit 11 may receive the data DATA, the data processing signal DMI andthe strobe signal DQS during the read operation. The controllertermination circuit 12 may be turned on during the read operation. Thecontroller termination circuit 12 may adjust a drivability thereofaccording to a resistance value of an I/O line IO through which the dataDATA, the data processing signal DMI and the strobe signal DQS aretransmitted, thereby driving the I/O line IO during the read operation.When the controller termination circuit 12 may be turned on, thecontroller termination circuit 12 may adjust a drivability of the I/Oline 10. The controller termination circuit 12 may be turned off duringthe write operation. When the controller termination circuit 12 may beturned off, the controller termination circuit 12 may not adjust adrivability of the I/O line IO. Although the I/O line IO is illustratedas a single line in FIG. 1, the I/O line IO may include a plurality oflines.

While the read operation is performed, the controller terminationcircuit 12 is turned on and the controller 10 may receive the data DATA,the data processing signal DMI and the strobe signal DQS through the I/Oline 10. While the write operation is performed, the controllertermination circuit 12 may be turned off and the controller 10 mayoutput the data DATA, the data processing signal DMI and the strobesignal DQS through the I/O line 10.

The first semiconductor device 20 may include a first internal I/Ocircuit 21, a first internal termination circuit (ODT1) 22 and a firstmemory circuit 23.

The first internal I/O circuit 21 may receive the data DATA according tothe first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> in synchronization with the clock signalCLK to generate first internal data ID1 during the write operation. Thefirst internal I/O circuit 21 may generate the data DATA from the firstinternal data ID1 according to the first chip selection signal CS1 andthe first to seventh command/address signals CA<1:7> in synchronizationwith the clock signal CLK during the read operation. The first internalI/O circuit 21 may receive the data processing signal DMI according tothe first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> in synchronization with the clock signalCLK to generate a first internal data processing signal IDMI1 during thewrite operation. The first internal I/O circuit 21 may generate the dataprocessing signal DMI from the first internal data processing signalIDMI1 according to the first chip selection signal CS1 and the first toseventh command/address signals CA<1:7> in synchronization with theclock signal CLK during the read operation. The first internal I/Ocircuit 21 may receive the strobe signal DQS according to the first chipselection signal CS1 and the first to seventh command/address signalsCA<1:7> in synchronization with the clock signal CLK to generate a firstinternal strobe signal IDQS1 during the write operation. The firstinternal I/O circuit 21 may generate the strobe signal DQS from thefirst internal strobe signal IDQS1 according to the first chip selectionsignal CS1 and the first to seventh command/address signals CA<1:7> insynchronization with the clock signal CLK during the read operation. Thefirst internal I/O circuit 21 may be synchronized with the clock signalCLK to generate a first pull-up drive signal PU1<1:4> and a firstpull-down drive signal PD1<1:4> for adjusting a drivability for drivingthe I/O line IO according to the first chip selection signal CS1 and thefirst to seventh command/address signals CA<1:7> during the readoperation. The first internal I/O circuit 21 may generate the firstpull-up drive signal PU1<1:4> and the first pull-down drive signalPD1<1:4> for setting a predetermined drivability if the secondsemiconductor device 30 performs the write operation or the readoperation. The word “predetermined” as used herein with respect to aparameter, such as a predetermined drivability, means that a value forthe parameter is determined prior to the parameter being used in aprocess or algorithm. For some embodiments, the value for the parameteris determined before the process or algorithm begins. In otherembodiments, the value for the parameter is determined during theprocess or algorithm but before the parameter is used in the process oralgorithm.

The first internal termination circuit 22 may drive the I/O line IO witha drivability which is adjusted according to the first pull-up drivesignal PU1<1:4> and the first pull-down drive signal PD1<1:4> during thewrite operation. The first internal termination circuit 22 may be turnedoff during the read operation to inhibit the I/O line IO from beingdriven. The first internal termination circuit 22 may be turned on todrive the I/O line IO with a predetermined drivability which is adjustedaccording to the first pull-up drive signal PU1<1:4> and the firstpull-down drive signal PD1<1:4> if the second semiconductor device 30performs the write operation or the read operation. When the firstinternal termination circuit 22 may be turned on, the first internaltermination circuit 22 may adjust a drivability of the I/O line IO. Whenthe first internal termination circuit 22 may be turned off, the firstinternal termination circuit 22 may not adjust a drivability of the I/Oline IO.

The first memory circuit 23 may store the first internal data ID1 duringthe write operation and may output the first internal data ID1 storedtherein during the read operation. The first memory circuit 23 may storethe first internal data processing signal IDMI1 during the writeoperation and may output the first internal data processing signal IDMI1stored therein during the read operation. The first memory circuit 23may store the first internal strobe signal IDQS1 during the writeoperation and may output the first internal strobe signal IDQS1 storedtherein during the read operation.

The second semiconductor device 30 may include a second internal I/Ocircuit 31, a second internal termination circuit (ODT2) 32 and a secondmemory circuit 33.

The second internal I/O circuit 31 may receive the data DATA accordingto the second chip selection signal CS2 and the first to seventhcommand/address signals CA<1:7> in synchronization with the clock signalCLK to generate second internal data ID2 during the write operation. Thesecond internal I/O circuit 31 may generate the data DATA from thesecond internal data ID2 according to the second chip selection signalCS2 and the first to seventh command/address signals CA<1:7> insynchronization with the clock signal CLK during the read operation. Thesecond internal I/O circuit 31 may receive the data processing signalDMI according to the second chip selection signal CS2 and the first toseventh command/address signals CA<1:7> in synchronization with theclock signal CLK to generate a second internal data processing signalIDMI2 during the write operation. The second internal I/O circuit 31 maygenerate the data processing signal DMI from the second internal dataprocessing signal IDMI2 according to the second chip selection signalCS2 and the first to seventh command/address signals CA<1:7> insynchronization with the clock signal CLK during the read operation. Thesecond internal I/O circuit 31 may receive the strobe signal DQSaccording to the second chip selection signal CS2 and the first toseventh command/address signals CA<1:7> in synchronization with theclock signal CLK to generate a second internal strobe signal IDQS2during the write operation. The second internal I/O circuit 31 maygenerate the strobe signal DQS from the second internal strobe signalIDQS2 according to the second chip selection signal CS2 and the first toseventh command/address signals CA<1:7> in synchronization with theclock signal CLK during the read operation. The second internal I/Ocircuit 31 may be synchronized with the clock signal CLK to generate asecond pull-up drive signal PU2<1:4> and a second pull-down drive signalPD2<1:4> for adjusting a drivability for driving the I/O line IOaccording to the second chip selection signal CS2 and the first toseventh command/address signals CA<1:7> during the read operation. Thesecond internal I/O circuit 31 may generate the second pull-up drivesignal PU2<1:4> and the second pull-down drive signal PD2<1:4> forsetting a predetermined drivability if the first semiconductor device 20performs the write operation or the read operation.

The second internal termination circuit 32 may drive the I/O line IOwith a drivability which is adjusted according to the second pull-updrive signal PU2<1:4> and the second pull-down drive signal PD2<1:4>during the write operation. The second internal termination circuit 32may be turned off during the read operation to inhibit the I/O line IOfrom being driven. The second internal termination circuit 32 may beturned on to drive the I/O line IO with a predetermined drivabilitywhich is adjusted according to the second pull-up drive signal PU2<1:4>and the second pull-down drive signal PD2<1:4> if the firstsemiconductor device 20 performs the write operation or the readoperation. When the second internal termination circuit 32 may be turnedon, the second internal termination circuit 32 may adjust a drivabilityof the I/O line IO. When the second internal termination circuit 32 maybe turned off, the second internal termination circuit 32 may not adjusta drivability of the I/O line IO.

The second memory circuit 33 may store the second internal data ID2during the write operation and may output the second internal data ID2stored therein during the read operation. The second memory circuit 33may store the second internal data processing signal IDMI2 during thewrite operation and may output the second internal data processingsignal IDMI2 stored therein during the read operation. The second memorycircuit 33 may store the second internal strobe signal IDQS2 during thewrite operation and may output the second internal strobe signal IDQS2stored therein during the read operation.

Referring to FIG. 2, the first internal I/O circuit 21 may include aninput buffer 100, a pulse generation circuit 200, an I/O control circuit300, a drive signal generation circuit 400 and a driver 500.

The input buffer 100 may be synchronized with a rising edge of the clocksignal CLK to generate an internal clock signal ICLK. The input buffer100 may be synchronized with a rising edge of the clock signal CLK togenerate an internal chip selection signal ICS from the first chipselection signal CS1. The input buffer 100 may be synchronized with arising edge of the clock signal CLK to generate first to seventhinternal command/address signals ICA<1:7> from the first to seventhcommand/address signals CA<1:7>.

The pulse generation circuit 200 may include a command decoder 210 and aflag signal generation circuit 220.

The command decoder 210 may be synchronized with the internal clocksignal ICLK to generate a write signal WT which is enabled if theinternal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> have a logic level combination forperforming the write operation. The command decoder 210 may besynchronized with the internal clock signal ICLK to generate a readsignal RD which is enabled if the internal chip selection signal ICS andthe first to seventh internal command/address signals ICA<1:7> have alogic level combination for performing the read operation.

The flag signal generation circuit 220 may shift the write signal WTaccording to a write latency signal WL to generate a write flag signalWTF. The flag signal generation circuit 220 may shift the read signal RDaccording to a read latency signal RL to generate a read flag signalRDF.

The I/O control circuit 300 may include a mode register 310 and a drivecontrol circuit 320.

The mode register 310 may be synchronized with the internal clock signalICLK to store information on a resistance value of the I/O line IO,which is included in the first to seventh internal command/addresssignals ICA<1:7>, according to the internal chip selection signal ICSand the first to seventh internal command/address signals ICA<1:7>during a mode register write operation. The information on theresistance value of the I/O line IO may be inputted to the mode register310 through certain bits included in the first to seventh internalcommand/address signals ICA<1:7>. The mode register 310 may besynchronized with the internal clock signal ICLK to store first andsecond target termination signals DQ_ODT<1:2>, first and secondnon-target termination signals NT_ODT<1:2>, the write latency signal WL,the read latency signal RL, a target termination operation signal ODTMRand a non-target termination operation signal NTMR according to theinternal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> during the mode register writeoperation. The first and second target termination signals DQ_ODT<1:2>,the first and second non-target termination signals NT_ODT<1:2>, thewrite latency signal WL, the read latency signal RL, the targettermination operation signal ODTMR and the non-target terminationoperation signal NTMR may be inputted to the mode register 310 throughcertain bits included in the first to seventh internal command/addresssignals ICA<1:7>. The mode register 310 may be synchronized with theinternal clock signal ICLK to output the resistance value information ofthe I/O line IO as first and second pre-pull-up control signalsPU_PRE<1:2> and first and second pre-pull-down control signalsPD_PRE<1:2> according to the internal chip selection signal ICS and thefirst to seventh internal command/address signals ICA<1:7> during a moderegister read operation. The mode register 310 may be synchronized withthe internal clock signal ICLK to output the first and second targettermination signals DQ_ODT<1:2>, the first and second non-targettermination signals NT_ODT<1:2>, the write latency signal WL, the readlatency signal RL, the target termination operation signal ODTMR and thenon-target termination operation signal NTMR according to the internalchip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> during the mode register readoperation. The mode register 310 may be synchronized with the internalclock signal ICLK to store a data process operation signal DMIMR and astrobe operation signal DQSMR according to the internal chip selectionsignal ICS and the first to seventh internal command/address signalsICA<1:7> during the mode register write operation. The data processoperation signal DMIMR and the strobe operation signal DQSMR may beinputted to the mode register 310 through certain bits included in thefirst to seventh internal command/address signals ICA<1:7>. The moderegister 310 may be synchronized with the internal clock signal ICLK tooutput the data process operation signal DMIMR and the strobe operationsignal DQSMR according to the internal chip selection signal ICS and thefirst to seventh internal command/address signals ICA<1:7> during themode register read operation.

The drive control circuit 320 may generate a data enablement signalOENDATA according to logic levels of the target termination operationsignal ODTMR and the non-target termination operation signal NTMR if thewrite flag signal WTF and the read flag signal RDF are inputted to thedrive control circuit 320. The drive control circuit 320 may generate adata process enablement signal OENDMI from the data process operationsignal DMIMR according to logic levels of the target terminationoperation signal ODTMR and the non-target termination operation signalNTMR if the write flag signal WTF and the read flag signal RDF areinputted to the drive control circuit 320. The drive control circuit 320may generate a strobe enablement signal OENDQS from the strobe operationsignal DQSMR according to logic levels of the target terminationoperation signal ODTMR and the non-target termination operation signalNTMR if the write flag signal WTF and the read flag signal RDF areinputted to the drive control circuit 320.

The drive control circuit 320 may generate first to fourth pull-upcontrol signals PUD<1:4> from the first and second pre-pull-up controlsignals PU_PRE<1:2> and may generate first to fourth pull-down controlsignals PDD<1:4> from the first and second pre-pull-down control signalsPD_PRE<1:2>, according to logic levels of the target terminationoperation signal ODTMR and the non-target termination operation signalNTMR if the write flag signal WTF is inputted to the drive controlcircuit 320. The drive control circuit 320 may generate the first tofourth pull-up control signals PUD<1:4> from the first and secondpre-pull-up control signals PU_PRE<1:2> and may generate the first tofourth pull-down control signals PDD<1:4> from the first and secondtarget termination signals DQ_ODT<1:2>, according to logic levels of thetarget termination operation signal ODTMR and the non-target terminationoperation signal NTMR if the write flag signal WTF is inputted to thedrive control circuit 320. The drive control circuit 320 may generatethe first to fourth pull-up control signals PUD<1:4> from the first andsecond pre-pull-up control signals PU_PRE<1:2> and may generate thefirst to fourth pull-down control signals PDD<1:4> from the first andsecond non-target termination signals NT_ODT<1:2>, according to logiclevels of the target termination operation signal ODTMR and thenon-target termination operation signal NTMR if the write flag signalWTF is inputted to the drive control circuit 320.

The drive signal generation circuit 400 may include a pull-up/pull-downsignal generation circuit 410 and a drive signal output circuit 420.

The pull-up/pull-down signal generation circuit 410 may generate apull-up signal PUON and a pull-down signal PDON, one of which isselectively enabled according to a logic level of the data DATA. Thepull-up/pull-down signal generation circuit 410 may generate the pull-upsignal PUON and the pull-down signal PDON, one of which is selectivelyenabled according to a logic level of the data processing signal DMI.The pull-up/pull-down signal generation circuit 410 may generate thepull-up signal PUON and the pull-down signal PDON, one of which isselectively enabled according to a logic level of the strobe signal DQS.For example, the pull-up/pull-down signal generation circuit 410 maygenerate the pull-up signal PUON which is enabled if the data DATA has alogic “high” level and may generate the pull-down signal PDON which isenabled if the data DATA has a logic “low” level. As used herein, asignal, such the data or chip selection signal etc., having a low leveldistinguishes from the signal when it has a high level. For example, thehigh level may correspond to the signal having a first voltage, and thelow level may correspond to the signal having a second voltage. For someembodiments, the first voltage is greater than the second voltage. Inother embodiments, different characteristics of a signal, such asfrequency or amplitude, determine whether the signal has a high level ora low level. For some cases, the high and low levels of a signalrepresent logical binary states.

The drive signal output circuit 420 may generate the first to fourthpull-up drive signals PU1<1:4> from the first to fourth pull-up controlsignals PUD<1:4> if the pull-up signal PUON is enabled. The drive signaloutput circuit 420 may generate the first to fourth pull-down drivesignals PD1<1:4> from the first to fourth pull-down control signalsPDD<1:4> if the pull-down signal PDON is enabled. The drive signaloutput circuit 420 may generate the first to fourth pull-down drivesignals PD1<1:4> from the first to fourth pull-down control signalsPDD<1:4> if the data enablement signal OENDATA is enabled.

The driver 500 may generate the data DATA from the first internal dataID1 during the read operation and may generate the first internal dataID1 from the data DATA if the data enablement signal OENDATA is enabledduring the write operation. The driver 500 may generate the dataprocessing signal DMI from the first internal data processing signalIDMI1 during the read operation and may generate the first internal dataprocessing signal IDMI1 from the data processing signal DMI if the dataprocess enablement signal OENDMI is enabled during the write operation.The driver 500 may generate the strobe signal DQS from the firstinternal strobe signal IDQS1 during the read operation and may generatethe first internal strobe signal IDQS1 from the strobe signal DQS if thestrobe enablement signal OENDQS is enabled during the write operation.

Edges of the clock signal CLK and logic levels of the chip selectionsignal CS and the first to seventh command/address signals CA<1:7> foractivating mode register write operations MRW1 and MRW2, a mode registerread operation MRR, a write operation WRITE and a write operation READperformed in an embodiment of the present disclosure will be describedhereinafter with reference to FIG. 3.

The mode register write operations MRW1 and MRW2 may include a firstmode register write operation MRW1 and a second mode register writeoperation MRW2. That is, the number of the mode register writeoperations may be set as two or more according to an amount ofinformation stored into the mode register 310. First, if the chipselection signal CS has a logic “high(H)” level and the first to seventhcommand/address signals CA<1:7> have a logic level combination of‘L,L,L,H,H,L,H’ at a rising edge of the clock signal CLK, thesemiconductor system 1 may be realized to perform the first moderegister write operation MRW1. In the first to seventh command/addresssignals CA<1:7>, the logic level combination of ‘L,L,L,H,H,L,H’ meansthat the first command/address signal CA<1> has a logic “low(L)” level,the second command/address signal CA<2> has a logic “low(L)” level, thethird command/address signal CA<3> has a logic “low(L)” level, thefourth command/address signal CA<4> has a logic “high(H)” level, thefifth command/address signal CA<5> has a logic “high(H)” level, thesixth command/address signal CA<6> has a logic “low(L)” level, and theseventh command/address signal CA<7> has a logic “high(H)” level.

Next, if the chip selection signal CS has a logic “high(H)” level andthe first to seventh command/address signals CA<1:7> have a logic levelcombination of ‘L,L,L,H,L,L,X’ at a rising edge of the clock signal CLK,the semiconductor system 1 may be realized to perform the second moderegister write operation MRW2. In the first to seventh command/addresssignals CA<1:7>, the logic level combination of ‘L,L,L,H,L,L,X’ meansthat the first command/address signal CA<1> has a logic “low(L)” level,the second command/address signal CA<2> has a logic “low(L)” level, thethird command/address signal CA<3> has a logic “low(L)” level, thefourth command/address signal CA<4> has a logic “high(H)” level, thefifth command/address signal CA<5> has a logic “low(L)” level, and thesixth command/address signal CA<6> has a logic “low(L)” level. In such acase, a logic state “X” of the seventh command/address signal CA<7> maycorrespond to a “DON'T CARE STATE”.

Next, if the chip selection signal CS has a logic “high(H)” level andthe first to seventh command/address signals CA<1:7> have a logic levelcombination of ‘L,L,L,H,H,L,L’ at a rising edge of the clock signal CLK,the semiconductor system 1 may be realized to perform the mode registerread operation MRR. In the first to seventh command/address signalsCA<1:7>, the logic level combination of ‘L,L,L,H,H,L,L’ means that thefirst command/address signal CA<1> has a logic “low(L)” level, thesecond command/address signal CA<2> has a logic “low(L)” level, thethird command/address signal CA<3> has a logic “low(L)” level, thefourth command/address signal CA<4> has a logic “high(H)” level, thefifth command/address signal CA<5> has a logic “high(H)” level, thesixth command/address signal CA<6> has a logic “low(L)” level, and theseventh command/address signal CA<7> has a logic “low(L)” level.

Next, if the chip selection signal CS has a logic “high(H)” level andthe first to seventh command/address signals CA<1:7> have a logic levelcombination of ‘L,L,H,X,X,X,X’ at a rising edge of the clock signal CLK,the semiconductor system 1 may be realized to perform the writeoperation WRITE. In the first to seventh command/address signalsCA<1:7>, the logic level combination of ‘L,L,H,X,X,X,X’ means that thefirst command/address signal CA<1> has a logic “low(L)” level, thesecond command/address signal CA<2> has a logic “low(L)” level, and thethird command/address signal CA<3> has a logic “high(H)” level. In sucha case, a logic state “X” of the fourth to seventh command/addresssignals CA<4:7> may correspond to a “DON'T CARE STATE”.

Finally, if the chip selection signal CS has a logic “high(H)” level andthe first to seventh command/address signals CA<1:7> have a logic levelcombination of ‘H,L,L,X,X,X,X’ at a rising edge of the clock signal CLK,the semiconductor system 1 may be realized to perform the read operationREAD. In the first to seventh command/address signals CA<1:7>, the logiclevel combination of ‘H,L,L,X,X,X,X’ means that the firstcommand/address signal CA<1> has a logic “high(H)” level, the secondcommand/address signal CA<2> has a logic “low(L)” level, and the thirdcommand/address signal CA<3> has a logic “low(L)” level. In such a case,a logic state “X” of the fourth to seventh command/address signalsCA<4:7> may also correspond to a “DON'T CARE STATE”.

Referring to FIG. 4, the drive control circuit 320 may include an ODTcontrol circuit 321, an enablement signal generation circuit 322 and acontrol signal generation circuit 323.

The ODT control circuit 321 may generate a target write signal WT_ODTand a non-target write signal WT_NT which are enabled at a point in timewhen the write flag signal WTF is inputted to the ODT control circuit321, according to the target termination operation signal ODTMR and thenon-target termination operation signal NTMR.

The enablement signal generation circuit 322 may generate the dataenablement signal OENDATA from the read flag signal RDF according to thenon-target termination operation signal NTMR during the read operation.The enablement signal generation circuit 322 may output the target writesignal WT_ODT as a pre-enablement signal ODTEN_PRE and may inverselybuffer the target write signal WT_ODT to generate the data enablementsignal OENDATA, according to the non-target termination operation signalNTMR during the write operation. The enablement signal generationcircuit 322 may generate the data process enablement signal OENDMI fromthe data process operation signal DMIMR according to the non-targettermination operation signal NTMR during the read operation and thewrite operation. The enablement signal generation circuit 322 maygenerate the strobe enablement signal OENDQS from the strobe operationsignal DQSMR according to the non-target termination operation signalNTMR during the read operation and the write operation.

The control signal generation circuit 323 may generate the first tofourth pull-up control signals PUD<1:4> from the first and secondpre-pull-up control signals PU_PRE<1:2> according to the non-targetwrite signal WT_NT. The control signal generation circuit 323 maygenerate the first to fourth pull-down control signals PDD<1:4> from thefirst and second pre-pull-down control signals PD_PRE<1:2> according tothe non-target write signal WT_NT. The control signal generation circuit323 may generate the first to fourth pull-down control signals PDD<1:4>from the first and second target termination signals DQ_ODT<1:2>according to the pre-enablement signal ODTEN_PRE. The control signalgeneration circuit 323 may generate the first to fourth pull-downcontrol signals PDD<1:4> from the first and second non-targettermination signals NT_ODT<1:2> according to the pre-enablement signalODTEN_PRE.

Referring to FIG. 5, the ODT control circuit 321 may be configured toperform NAND logic operations and may be realized using, for example butnot limited to, NAND gates NAND11 and NAND12.

The NAND gate NAND11 may generate the target write signal WT_ODT whichis enabled to have a logic “low” level at a point in time when thetarget termination operation signal ODTMR having a logic “high” leveland the write flag signal WTF having a logic “high” level are inputtedto the NAND gate NAND11.

The NAND gate NAND12 may generate the non-target write signal WT_NTwhich is enabled to have a logic “high” level if the non-targettermination operation signal NTMR having a logic “high” level and thetarget write signal WT_ODT having a logic “low” level are inputted tothe NAND gate NAND12.

Referring to FIG. 6, the enablement signal generation circuit 322 may beconfigured to perform NAND and inversion operations and may be realizedusing, for example but not limited to, a multiplexer MUX21, an inverterIV21 and NAND gates NAND21 and NAND22.

The multiplexer MUX21 may output the target write signal WT_ODT as thepre-enablement signal ODTEN_PRE if the non-target termination operationsignal NTMR has a logic “low” level. The multiplexer MUX21 may outputthe read flag signal RDF as the pre-enablement signal ODTEN_PRE if thenon-target termination operation signal NTMR has a logic “high” level.

The inverter IV21 may inversely buffer the pre-enablement signalODTEN_PRE to generate the data enablement signal OENDATA.

The NAND gate NAND21 may inversely buffer the data process operationsignal DMIMR to generate the data process enablement signal OENDMI ifthe pre-enablement signal ODTEN_PRE is enabled to have a logic “high”level.

The NAND gate NAND22 may inversely buffer the strobe operation signalDQSMR to generate the strobe enablement signal OENDQS if thepre-enablement signal ODTEN_PRE is enabled to have a logic “high” level.

Referring to FIG. 7, the control signal generation circuit 323 mayinclude a decoded signal generation circuit 3100 and aselection/transmission circuit 3200.

The decoded signal generation circuit 3100 may include a first decoder3110, a second decoder 3120, a third decoder 3130 and a fourth decoder3140.

The first decoder 3110 may decode the first and second non-targettermination signals NT_ODT<1:2> to generate first to fourth non-targetdecoded signals NT_DEC<1:4>.

The second decoder 3120 may decode the first and second targettermination signals DQ_ODT<1:2> to generate first to fourth targetdecoded signals DQ_DEC<1:4>.

The third decoder 3130 may decode the first and second pre-pull-downcontrol signals PD_PRE<1:2> to generate first to fourth pull-downdecoded signals PD_DEC<1:4>.

The fourth decoder 3140 may decode the first and second pre-pull-upcontrol signals PU_PRE<1:2> to generate the first to fourth pull-upcontrol signals PUD<1:4>.

The selection/transmission circuit 3200 may include multiplexers MUX31and MUX32.

The multiplexer MUX31 may output the first to fourth non-target decodedsignals NT_DEC<1:4> as first to fourth selection signals SEL<1:4> if thenon-target write signal WT_NT has a logic “low” level. The multiplexerMUX31 may output the first to fourth target decoded signals DQ_DEC<1:4>as the first to fourth selection signals SEL<1:4> if the non-targetwrite signal WT_NT has a logic “high” level.

The multiplexer MUX32 may output the first to fourth selection signalsSEL<1:4> as the first to fourth pull-down control signals PDD<1:4> ifthe pre-enablement signal ODTEN_PRE has a logic “low” level. Themultiplexer MUX32 may output the first to fourth pull-down decodedsignals PD_DEC<1:4> as the first to fourth pull-down control signalsPDD<1:4> if the pre-enablement signal ODTEN_PRE has a logic “high”level.

Referring to FIG. 8, the drive signal output circuit 420 may include apull-up drive signal output circuit 421 and a pull-down drive signaloutput circuit 422.

The pull-up drive signal output circuit 421 may output the first tofourth pull-up control signals PUD<1:4> as the first to fourth pull-updrive signals PU1<1:4> if the pull-up signal PUON is enabled.

The pull-down drive signal output circuit 422 may output the first tofourth pull-down control signals PDD<1:4> as the first to fourthpull-down drive signals PD1<1:4> if the pull-down signal PDON isenabled. The pull-down drive signal output circuit 422 may output thefirst to fourth pull-down control signals PDD<1:4> as the first tofourth pull-down drive signals PD1<1:4> if the data enablement signalOENDATA is enabled.

Referring to FIG. 9, the pull-down drive signal output circuit 422 mayinclude a transmission control signal generation circuit 4100 and asignal transmission circuit 4200.

The transmission control signal generation circuit 4100 may beconfigured to perform an OR logic operation and may be realized using,for example but not limited to, an OR gate OR41.

The transmission control signal generation circuit 4100 may generate atransmission control signal TCON which is enabled to have a logic “high”level if any one of the pull-down signal PDON and the data enablementsignal OENDATA is enabled to have a logic “high” level. The transmissioncontrol signal generation circuit 4100 may perform a logical “OR”operation of the pull-down signal PDON and the data enablement signalOENDATA to generate the transmission control signal TCON.

The signal transmission circuit 4200 may be configured to perform an ANDlogic operation and may be realized using, for example but not limitedto, AND gates AND41, AND42, AND43 and AND44.

The AND gate AND41 may output the first pull-down control signal PDD<1>as the first pull-down drive signal PD1<1> if the transmission controlsignal TCON is enabled to have a logic “high” level.

The AND gate AND42 may output the second pull-down control signal PDD<2>as the second pull-down drive signal PD1<2> if the transmission controlsignal TCON is enabled to have a logic “high” level.

The AND gate AND43 may output the third pull-down control signal PDD<3>as the third pull-down drive signal PD1<3> if the transmission controlsignal TCON is enabled to have a logic “high” level.

The AND gate AND44 may output the fourth pull-down control signal PDD<4>as the fourth pull-down drive signal PD1<4> if the transmission controlsignal TCON is enabled to have a logic “high” level.

The second internal I/O circuit 31 of the second semiconductor device 30may be realized using substantially the same circuit as the firstinternal I/O circuit 21 described with reference to FIGS. 1 to 9 exceptI/O signals thereof. Thus, a description of the second internal I/Ocircuit 31 will be omitted hereinafter.

An operation of the semiconductor system 1 according to an embodimentwill be described hereinafter with reference to FIG. 10 in conjunctionwith an example in which only the first semiconductor device 20 performsthe write operation.

At a point of time “T11”, the controller 10 may output the clock signalCLK, the first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> for performing the write operation.Because the first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> are signals which are generated toperform the write operation, the controller termination circuit 12 ofthe controller 10 may be turned off.

The input buffer 100 of the first internal I/O circuit 21 may besynchronized with a rising edge of the clock signal CLK to generate theinternal clock signal ICLK, to generate the internal chip selectionsignal ICS from the first chip selection signal CS1, and to generate thefirst to seventh internal command/address signals ICA<1:7> from thefirst to seventh command/address signals CA<1:7>.

The pulse generation circuit 200 of the first internal I/O circuit 21may be synchronized with the internal clock signal ICLK to generate thewrite signal WT which is enabled to have a logic “high” level becausethe internal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> have a logic level combination forperforming the write operation. The pulse generation circuit 200 may besynchronized with the internal clock signal ICLK to generate the readsignal RD which is disabled to have a logic “low” level because theinternal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> have a logic level combination forperforming the write operation.

At a point of time “T12”, the pulse generation circuit 200 of the firstinternal I/O circuit 21 may shift the write signal WT according to thewrite latency signal WL to generate the write flag signal WTF having alogic “high” level. In such a case, the pulse generation circuit 200 maygenerate the read flag signal RDF having a logic “low” level.

The ODT control circuit 321 of the drive control circuit 320 maygenerate the target write signal WT_ODT enabled to have a logic “low”level and the non-target write signal WT_NT having a logic “high” level,according to the target termination operation signal ODTMR having alogic “high” level and the non-target termination operation signal NTMRhaving a logic “low” level.

The enablement signal generation circuit 322 of the drive controlcircuit 320 may output the target write signal WT_ODT having a logic“low” level as the pre-enablement signal ODTEN_PRE according to thenon-target termination operation signal NTMR having a logic “low” level.The enablement signal generation circuit 322 may inversely buffer thetarget write signal WT_ODT to generate the data enablement signalOENDATA having a logic “high” level.

The control signal generation circuit 323 of the drive control circuit320 may generate the first to fourth pull-up control signals PUD<1:4>from the first and second pre-pull-up control signals PU_PRE<1:2> andmay generate the first to fourth pull-down control signals PDD<1:4> fromthe first and second target termination signals DQ_ODT<1:2> according tothe non-target write signal WT_NT having a logic “high” level.

The drive signal output circuit 420 may generate the first to fourthpull-up drive signals PU1<1:4> from the first to fourth pull-up controlsignals PUD<1:4> and may generate the first to fourth pull-down drivesignals PD1<1:4> from the first to fourth pull-down control signalsPDD<1:4>. That is, the first to fourth pull-down drive signals PD1<1:4>may be generated from the first and second target termination signalsDQ_ODT<1:2>.

At a point of time “T13”, the external I/O circuit 11 of the controller10 may output the data DATA through the I/O line 10.

The driver 500 may generate the first internal data ID1 from the dataDATA according to the data enablement signal OENDATA having a logic“high” level.

The first internal termination circuit 22 may drive the I/O line IO witha drivability which is adjusted according to the first to fourth pull-updrive signals PU1<1:4> and the first to fourth pull-down drive signalsPD1<1:4>. In such a case, because the I/O line IO is driven by theadjusted drivability, it may be possible to suppress or reduce areflection phenomenon of the data DATA.

The first semiconductor circuit 23 may store the first internal dataID1.

A time period from the point of time “T11” till the point of time “T13”may be set as a write latency period.

If the write operation terminates after a point of time “T14”, the writeflag signal WTF may be disabled to have a logic “low” level to inhibitthe generation of the first to fourth pull-up drive signals PU1<1:4> andthe first to fourth pull-down drive signals PD1<1:4>. That is, the firstinternal termination circuit 22 may terminate driving the I/O line IOaccording to the first to fourth pull-up drive signals PU1<1:4> and thefirst to fourth pull-down drive signals PD1<1:4>.

An operation of the semiconductor system 1 according to an embodimentwill be described hereinafter with reference to FIG. 11 in conjunctionwith an example in which the first semiconductor device 20 of the firstand second semiconductor devices 20 and 30 performs the write operation.

At a point of time “T21”, the controller 10 may output the clock signalCLK, the first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> for performing the write operation.Because the first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> are signals which are generated toperform the write operation, the controller termination circuit 12 ofthe controller 10 may be turned off.

The input buffer 100 of the first internal I/O circuit 21 may besynchronized with a rising edge of the clock signal CLK to generate theinternal clock signal ICLK, to generate the internal chip selectionsignal ICS from the first chip selection signal CS1, and to generate thefirst to seventh internal command/address signals ICA<1:7> from thefirst to seventh command/address signals CA<1:7>.

The pulse generation circuit 200 of the first internal I/O circuit 21may be synchronized with the internal clock signal ICLK to generate thewrite signal WT which is enabled to have a logic “high” level becausethe internal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> have a logic level combination forperforming the write operation. The pulse generation circuit 200 may besynchronized with the internal clock signal ICLK to generate the readsignal RD which is disabled to have a logic “low” level because theinternal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> have a logic level combination forperforming the write operation.

At a point of time “T22”, the pulse generation circuit 200 of the firstinternal I/O circuit 21 may shift the write signal WT according to thewrite latency signal WL to generate the write flag signal WTF having alogic “high” level. In such a case, the pulse generation circuit 200 maygenerate the read flag signal RDF having a logic “low” level.

The ODT control circuit 321 of the drive control circuit 320 maygenerate the target write signal WT_ODT enabled to have a logic “low”level and the non-target write signal WT_NT having a logic “high” level,according to the target termination operation signal ODTMR having alogic “high” level and the non-target termination operation signal NTMRhaving a logic “high” level.

The enablement signal generation circuit 322 of the drive controlcircuit 320 may output the read flag signal RDF having a logic “low”level as the pre-enablement signal ODTEN_PRE according to the non-targettermination operation signal NTMR having a logic “high” level. Theenablement signal generation circuit 322 may inversely buffer the readflag signal RDF to generate the data enablement signal OENDATA having alogic “high” level.

The control signal generation circuit 323 of the drive control circuit320 may generate the first to fourth pull-up control signals PUD<1:4>from the first and second pre-pull-up control signals PU_PRE<1:2> andmay generate the first to fourth pull-down control signals PDD<1:4> fromthe first and second target termination signals DQ_ODT<1:2> according tothe non-target write signal WT_NT having a logic “high” level.

The drive signal output circuit 420 may generate the first to fourthpull-up drive signals PU1<1:4> from the first to fourth pull-up controlsignals PUD<1:4> and may generate the first to fourth pull-down drivesignals PD1<1:4> from the first to fourth pull-down control signalsPDD<1:4>. That is, the first to fourth pull-down drive signals PD1<1:4>may be generated from the first and second target termination signalsDQ_ODT<1:2>.

At a point of time “T23”, the external I/O circuit 11 of the controller10 may output the data DATA through the I/O line IO.

The driver 500 may generate the first internal data ID1 from the dataDATA according to the data enablement signal OENDATA having a logic“high” level.

The first internal termination circuit 22 may drive the I/O line IO witha drivability which is adjusted according to the first to fourth pull-updrive signals PU1<1:4> and the first to fourth pull-down drive signalsPD1<1:4>. In such a case, because the I/O line IO is driven by theadjusted drivability, it may be possible to suppress or reduce areflection phenomenon of the data DATA.

The first semiconductor circuit 23 may store the first internal dataID1.

A time period from the point of time “T21” till the point of time “T23”may be set as a write latency period.

After a point of time “T24”, the write flag signal WTF may be disabledto have a logic “low” level to inhibit the generation of the first tofourth pull-up drive signals PU1<1:4> and the first to fourth pull-downdrive signals PD1<1:4>. That is, the first internal termination circuit22 may terminate driving the I/O line IO according to the first tofourth pull-up drive signals PU1<1:4> and the first to fourth pull-downdrive signals PD1<1:4>.

An operation of the semiconductor system 1 according to an embodimentwill be described hereinafter with reference to FIG. 12 in conjunctionwith an example in which the first semiconductor device 20 of the firstand second semiconductor devices 20 and 30 performs the read operation.

At a point of time “T31”, the controller 10 may output the clock signalCLK, the first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> for performing the read operation.Because the first chip selection signal CS1 and the first to seventhcommand/address signals CA<1:7> are signals which are generated toperform the read operation, the controller termination circuit 12 of thecontroller 10 may be turned on.

The input buffer 100 of the first internal I/O circuit 21 may besynchronized with a rising edge of the clock signal CLK to generate theinternal clock signal ICLK, to generate the internal chip selectionsignal ICS from the first chip selection signal CS1, and to generate thefirst to seventh internal command/address signals ICA<1:7> from thefirst to seventh command/address signals CA<1:7>.

The pulse generation circuit 200 of the first internal I/O circuit 21may be synchronized with the internal clock signal ICLK to generate theread signal RD which is enabled to have a logic “high” level because theinternal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> have a logic level combination forperforming the read operation. The pulse generation circuit 200 may besynchronized with the internal clock signal ICLK to generate the writesignal WT which is disabled to have a logic “low” level because theinternal chip selection signal ICS and the first to seventh internalcommand/address signals ICA<1:7> have a logic level combination forperforming the read operation.

At a point of time “T32”, the pulse generation circuit 200 of the firstinternal I/O circuit 21 may shift the read signal RD according to theread latency signal RL to generate the read flag signal RDF having alogic “high” level. In such a case, the pulse generation circuit 200 maygenerate the write flag signal WTF having a logic “low” level.

The ODT control circuit 321 of the drive control circuit 320 maygenerate the target write signal WT_ODT disabled to have a logic “high”level and the non-target write signal WT_NT having a logic “low” level,according to the write flag signal WTF having a logic “low” level, thetarget termination operation signal ODTMR having a logic “high” leveland the non-target termination operation signal NTMR having a logic“high” level.

The enablement signal generation circuit 322 of the drive controlcircuit 320 may output the read flag signal RDF having a logic “high”level as the pre-enablement signal ODTEN_PRE according to the non-targettermination operation signal NTMR having a logic “high” level. Theenablement signal generation circuit 322 may inversely buffer the readflag signal RDF to generate the data enablement signal OENDATA having alogic “low” level.

The control signal generation circuit 323 of the drive control circuit320 may generate the first to fourth pull-up control signals PUD<1:4>from the first and second pre-pull-up control signals PU_PRE<1:2> andmay generate the first to fourth pull-down control signals PDD<1:4> fromthe first and second pre-pull-down control signals PD_PRE<1:2> accordingto the pre-enablement signal ODTEN_PRE having a logic “high” level.

The drive signal output circuit 420 may generate the first to fourthpull-up drive signals PU1<1:4> from the first to fourth pull-up controlsignals PUD<1:4> and may generate the first to fourth pull-down drivesignals PD1<1:4> from the first to fourth pull-down control signalsPDD<1:4>. That is, the first to fourth pull-down drive signals PD1<1:4>may be generated from the first and second pre-pull-down control signalsPD_PRE<1:2>.

At a point of time “T33”, the driver 500 may generate the data DATA fromthe first internal data ID1 according to the data enablement signalOENDATA having a logic “low” level.

The first internal termination circuit 22 may drive the I/O line IO witha drivability which is adjusted according to the first to fourth pull-updrive signals PU1<1:4> and the first to fourth pull-down drive signalsPD1<1:4>.

The external I/O circuit 11 of the controller 10 may receive the dataDATA through the I/O line IO. The controller termination circuit 12 maybe turned on to drive the I/O line IO. In such a case, because the I/Oline IO is driven by the adjusted drivability which is matched with aresistance value of the I/O line IO, it may be possible to suppress orreduce a reflection phenomenon of the data DATA.

A time period from the point of time “T31” till the point of time “T33”may be set as a read latency period.

If the read operation terminates after a point of time “T34”, the I/Oline IO is not driven.

A semiconductor system having an aforementioned configuration mayselectively drive some of the termination circuits included in acontroller and a plurality of semiconductor devices to preventreflection of I/O signals loaded on I/O lines during a read operationand a write operation. In addition, the semiconductor system may drivethe termination circuits included in the semiconductor devices notperforming the read operation and the write operation to prevent thereflection of the I/O signals loaded on the I/O lines which are sharedby the semiconductor devices. Accordingly, the reliability andperformance of the semiconductor system may be improved.

Referring to FIG. 13, a semiconductor device 1000 according to anembodiment may include a command control circuit 1101, a latency/burstcontrol circuit 1102, an operation control circuit 1103, an input/output(I/O) control circuit 1104, a data I/O circuit 1105 and a DRAM core1106.

The command control circuit 1101 may include an input drive circuit1111, a chip selection signal buffer 1112, a command/address buffer1113, a command decoder 1114 and a power-down control circuit 1115. Theinput drive circuit 1111 may receive and drive a chip selection signalCS to transmit the chip selection signal CS to the power-down controlcircuit 1115. The chip selection signal buffer 1112 may buffer the chipselection signal CS based on a chip selection reference voltage VREF_CS.The command/address buffer 1113 may buffer a command/address signalCA<0:6> based on a command/address reference voltage VREF_CA. Thecommand decoder 1114 may decode the command/address signal CA<0:6>buffered by the command/address buffer 1113 based on the chip selectionsignal CS buffered by the chip selection signal buffer 1112 to generatevarious commands necessary for the operation of the semiconductor device1000. The power-down control circuit 1115 may control a power-down modebased on the chip selection signal CS driven by the input drive circuit1111 and a command generated by the command decoder 1114.

The latency/burst control circuit 1102 may include a burst lengthinformation generator 1121, a write latency controller 1122 and a burstlength control circuit 1123. The burst length information generator 1121may generate information necessary for control of a burst lengthoperation based on a command generated by the command decoder 1114. Thewrite latency controller 1122 may perform a control operation accordingto a write latency based on a command generated by the command decoder1114. The burst length control circuit 1123 may include an informationstorage circuit 1125 storing information outputted from the burst lengthinformation generator 1121. The burst length control circuit 1123 mayinclude a burst length controller 1126 for controlling the burst lengthoperation based on a command generated by the command decoder 1114, asignal outputted from the write latency controller 1122, and informationoutputted from the burst length information generator 1121. The burstlength control circuit 1123 may include a burst end controller 1127 forcontrolling a burst end operation based on a command generated by thecommand decoder 1114, a signal outputted from the write latencycontroller 1122, and information outputted from the burst lengthinformation generator 1121.

The operation control circuit 1103 may include a read/write controller1131, an address controller 1132, an auto-pre-charge controller 1133 anda row path controller 1134 to generate a read/write control signalRD/WR_Control for controlling a read operation and a write operation aswell as a row path control signal ACT/PCG/REF_Control for controlling anactive operation, a pre-charge operation and a refresh operation. Theread/write controller 1131 may control the read operation and the writeoperation based on a signal outputted from the latency/burst controlcircuit 1102 and a signal outputted from the address controller 1132 ifclock signals CK_t and CK_c are activated. The address controller 1132may control generation of an address based on a signal outputted fromthe latency/burst control circuit 1102. The auto-pre-charge controller1133 may control an auto-pre-charge operation based on a signaloutputted from the latency/burst control circuit 1102 if the clocksignals CK_t and CK_c are activated. The row path controller 1134 maycontrol a row path based on a command generated by the command decoder1114.

The I/O control circuit 1104 may include a first clock buffer 1141, aclock enablement signal generator 1142, a second clock buffer 1143, afirst divider 1144, a second divider 1145, an internal clock driver1146, an I/O controller 1147 and a data path controller 1148. The firstclock buffer 1141 may receive and buffer the clock signals CK_t andCK_c. The clock enablement signal generator 1142 may generate a clockenablement signal after the clock signals CK_t and CK_c buffered by thefirst clock buffer 241 are activated. The second clock buffer 1143 mayreceive and buffer data clock signals WCK and WCKB for input and outputof the data. The first divider 1144 may divide the data clock signalsWCK and WCKB buffered by the second clock buffer 1143. The seconddivider 1145 may receive and divide an output signal of the firstdivider 1144. The internal clock driver 1146 may receive and divide anoutput signal of the first divider 1144 to generate an internal dataclock signal IWCK[0:3]. The I/O controller 1147 may receive a signaldivided by the second divider 1145 and the internal data clock signalIWCK[0:3] generated by the internal clock driver 1146 to control theinput and output of the data. The data path controller 1148 may controla data path used in the input and output of the data, based on a signaloutputted from the I/O controller 1147 and the internal data clocksignal IWCK[0:3] generated by the internal clock driver 1146.

The data I/O circuit 1105 may include a receiver 1151, a deserializer1152, a write driver 1153, a write multiplexer 1154, a read multiplexer1155, a read driver 1156, a serializer 1157 and a transmitter 1158. Thereceiver 1151 may be synchronized with the internal data clock signalIWCK[0:3] to receive transmission data DQ based on a data referencevoltage VREF_DQ. The deserializer 1152 may convert the transmission dataDQ inputted in series through the receiver 1151 into parallel data. Thewrite driver 1153 may drive the parallel data to transmit the drivenparallel data to the write multiplexer 1154. The write multiplexer 1154may transmit the data driven by the write driver 1153 to the DRAM core1106 using a multiplexing technique with an I/O line. The readmultiplexer 1155 may output the data outputted from the DRAM core 1106through the I/O line to the read driver 1156 using a multiplexingtechnique during the read operation. The read driver 1156 may drive thedata outputted from the DRAM core 1106 through the read multiplexer 1155to output the driven data to the serializer 1157. The serializer 1157may convert the data outputted from the read driver 1156 into serialdata. The transmitter 1158 may output the serial data converted by theserializer 1157 as the transmission data DQ.

The DRAM core 1106 may perform the read operation or the write operationfor outputting or receiving the data through the data I/O circuit 1105based on the read/write control signal RD/WR_Control. The DRAM core 1106may perform the active operation, the pre-charge operation or therefresh operation based on the row path control signalACT/PCG/REF_Control.

The semiconductor device 1000 illustrated in FIG. 13 may be applied toeach of the first semiconductor device 20 and the second semiconductordevice 300 included in the semiconductor system 1 according to anembodiment except I/O signals thereof.

What is claimed is:
 1. A semiconductor system comprising: a controllerconfigured to output a clock signal, a chip selection signal and acommand and address (command/address) signal, the controller including acontroller termination circuit turned on during a read operation andconfigured to receive first data through an input/output (I/O) linecoupled to the controller termination circuit during the read operation,and the controller configured to output second data through the I/O linecoupled to the controller termination circuit turned off during a writeoperation; and a semiconductor device including an internal terminationcircuit configured to turned off during the read operation, thesemiconductor device configured to output the first data through the I/Oline coupled to the internal termination circuit based on the chipselection signal and the command/address signal during the readoperation, and the semiconductor device configured to store the seconddata inputted through the I/O line coupled to the internal terminationcircuit turned on during the write operation.
 2. The semiconductorsystem of claim 1, wherein a drivability of the controller terminationcircuit is adjusted to be matched with a resistance value of the I/Oline during the read operation; and wherein a drivability of theinternal termination circuit is adjusted to be matched with a resistancevalue of the I/O line during the write operation.
 3. The semiconductorsystem of claim 1, wherein the controller outputs information on aresistance value of the I/O line through the command/address signalduring a mode register write operation.
 4. The semiconductor system ofclaim 1, wherein the semiconductor device comprises: an internal I/Ocircuit configured to be synchronized with the clock signal to generateinternal data from the second data during the write operation based onthe chip selection signal and the command/address signal, to generatethe first data from the internal data during the read operation based onthe chip selection signal and the command/address signal, and togenerate a pull-up drive signal and a pull-down drive signal foradjusting the drivability for driving the I/O line based on the chipselection signal and the command/address signal; an internal terminationcircuit configured to drive the I/O line with the drivability adjustedbased on the pull-up drive signal and the pull-down drive signal duringthe write operation; and a memory circuit configured to store theinternal data during the write operation and configured to output thestored internal data during the read operation.
 5. The semiconductorsystem of claim 4, wherein the internal I/O circuit is configured tostore information on a resistance value of the I/O line, which isinputted through the command/address signal, during a mode registerwrite operation; and wherein the internal I/O circuit is configured tooutput the information on the resistance value of the I/O line during amode register read operation.
 6. The semiconductor system of claim 4,wherein the internal I/O circuit comprises: an input buffer configuredto be synchronized with the clock signal to generate an internal clocksignal, configured to be synchronized with the clock signal to generatean internal chip selection signal from the chip selection signal, andconfigured to be synchronized with the clock signal to generate aninternal command/address signal from the command/address signal; a pulsegeneration circuit configured to generate a write flag signal which isenabled during the write operation based on a logic level combination ofthe internal chip selection signal and the internal command/addresssignal and configured to generate a read flag signal which is enabledduring the read operation based on a logic level combination of theinternal chip selection signal and the internal command/address signal;an I/O control circuit configured to generate a pull-up control signaland a pull-down control signal from information on a resistance value ofthe I/O line based on the write flag signal during the write operationand configured to generate a data enablement signal based on theinternal command/address signal during the write operation; a drivesignal generation circuit configured to receive the second data togenerate the pull-up drive signal and the pull-down drive signal fromthe pull-up control signal and the pull-down control signal; and adriver configured to generate the first data from the internal dataduring the read operation and configured to generate the internal datafrom the second data when the data enablement signal is inputted duringthe write operation.
 7. The semiconductor system of claim 6, wherein thepulse generation circuit comprises: a command decoder configured to besynchronized with the internal clock signal to generate a write signalwhich is enabled when the internal chip selection signal and theinternal command/address signal have a logic level combination forperforming the write operation and configured to be synchronized withthe internal clock signal to generate a read signal which is enabledwhen the internal chip selection signal and the internal command/addresssignal have a logic level combination for performing the read operation;and a flag signal generation circuit configured to shift the writesignal based on a write latency signal to generate the write flag signaland configured to shift the read signal based on a read latency signalto generate the read flag signal.
 8. The semiconductor system of claim6, wherein the I/O control circuit comprises: a mode register configuredto be synchronized with the internal clock signal to store informationon a resistance value of the I/O line, which is inputted through theinternal command/address signal, a target termination signal, a writelatency signal, a read latency signal and a target termination operationsignal based on the internal chip selection signal and the internalcommand/address signal during a mode register write operation,configured to be synchronized with the internal clock signal to outputthe resistance value information of the I/O line as a pre-pull-upcontrol signal and a pre-pull-down control signal based on the internalchip selection signal and the internal command/address signal during amode register read operation, and configured to be synchronized with theinternal clock signal to output the stored target termination signal,the stored write latency signal, the stored read latency signal and thestored target termination operation signal based on the internal chipselection signal and the internal command/address signal during the moderegister read operation; and a drive control circuit configured togenerate the data enablement signal from the target terminationoperation signal when the write flag signal is inputted to the drivecontrol circuit and configured to generate the pull-up control signaland the pull-down control signal from the pre-pull-up control signal andthe pre-pull-down control signal when the write flag signal is inputtedto the drive control circuit.
 9. The semiconductor system of claim 8,wherein the drive control circuit comprises: an on-die termination (ODT)control circuit configured to generate a target write signal which isenabled at a point in time when the write flag signal is inputted to theODT control circuit while the target termination operation signal isenabled; an enablement signal generation circuit configured to generatethe data enablement signal from the read flag signal during the readoperation, configured to output the target write signal as apre-enablement signal during the write operation, and configured toinversely buffer the target write signal to generate the data enablementsignal; and a control signal generation circuit configured to generatethe pull-up control signal from the pre-pull-up control signal andconfigured to generate the pull-down control signal from the targettermination signal or the pre-pull-down control signal based on thepre-enablement signal.
 10. The semiconductor system of claim 6, whereinthe drive signal generation circuit comprises: a pull-up/pull-downsignal generation circuit configured to generate a pull-up signal and apull-down signal, one of which is selectively enabled based on a logiclevel of the second data; and a drive signal output circuit configuredto generate the pull-up drive signal and the pull-down drive signal fromthe pull-up control signal and the pull-down control signal when thepull-up signal and the pull-down signal are enabled.
 11. Thesemiconductor system of claim 10, wherein the drive signal outputcircuit comprises: a pull-up drive signal output circuit configured tooutput the pull-up control signal as the pull-up drive signal when thepull-up signal is enabled; and a pull-down drive signal output circuitconfigured to output the pull-down control signal as the pull-down drivesignal when the pull-down signal or the data enablement signal isenabled.
 12. A semiconductor system comprising: a controller configuredto output a clock signal, first and second chip selection signals and acommand/address signal and configured to include a controllertermination circuit which is turned on during a read operation andturned off during a write operation; a first semiconductor deviceconfigured to include a first internal termination circuit which isturned off during the read operation and the write operation based onthe first chip selection signal and the command/address signal; and asecond semiconductor device configured to include a second internaltermination circuit which is turned on during the read operation and thewrite operation based on the second chip selection signal and thecommand/address signal, wherein the controller termination circuit, thefirst internal termination circuit and the second internal terminationcircuit share an input/output (I/O) line with each other to be driven.13. The semiconductor system of claim 12, wherein the controllerreceives first data through the I/O line during the read operation andoutputs second data through the I/O line during the write operation; andwherein the first semiconductor device outputs the first data throughthe I/O line during the read operation and receives and stores thesecond data during the write operation.
 14. The semiconductor system ofclaim 12, wherein a drivability of the controller termination circuit isadjusted to be matched with a resistance value of the I/O line duringthe read operation; and wherein a drivability of the first internaltermination circuit is adjusted to be matched with a resistance value ofthe I/O line during the write operation.
 15. The semiconductor system ofclaim 12, wherein the second internal termination circuit is configuredto drive the I/O line with a predetermined drivability during the readoperation and the write operation.
 16. The semiconductor system of claim12, wherein the first semiconductor device comprises: a first internalI/O circuit configured to be synchronized with the clock signal togenerate first internal data from second data loaded on the I/O lineduring the write operation based on the first chip selection signal andthe command/address signal, to generate first data from the firstinternal data and to output the first data through the I/O line duringthe read operation based on the first chip selection signal and thecommand/address signal, and to generate a first pull-up drive signal anda first pull-down drive signal for adjusting a drivability for drivingthe I/O line based on the first chip selection signal and thecommand/address signal; a first internal termination circuit configuredto drive the I/O line with the drivability adjusted based on the firstpull-up drive signal and the first pull-down drive signal during thewrite operation; and a first memory circuit configured to store thefirst internal data during the write operation and configured to outputthe stored first internal data during the read operation.
 17. Thesemiconductor system of claim 16, wherein the first internal I/O circuitis configured to store information on a resistance value of the I/Oline, which is inputted through the command/address signal, during amode register write operation; and wherein the first internal I/Ocircuit is configured to output the information on the resistance valueof the I/O line during a mode register read operation.
 18. Thesemiconductor system of claim 16, wherein the first internal I/O circuitcomprises: a first input buffer configured to be synchronized with theclock signal to generate a first internal clock signal, configured to besynchronized with the clock signal to generate a first internal chipselection signal from the first chip selection signal, and configured tobe synchronized with the clock signal to generate a first internalcommand/address signal from the command/address signal; a first pulsegeneration circuit configured to generate a first write flag signalwhich is enabled during the write operation based on a logic levelcombination of the first internal chip selection signal and the firstinternal command/address signal and configured to generate a first readflag signal which is enabled during the read operation based on a logiclevel combination of the first internal chip selection signal and thefirst internal command/address signal; a first I/O control circuitconfigured to generate a first pull-up control signal and a firstpull-down control signal from information on a resistance value of theI/O line based on the first write flag signal during the write operationand configured to generate a first data enablement signal based on thefirst internal command/address signal during the write operation; afirst drive signal generation circuit configured to receive the seconddata to generate the first pull-up drive signal and the first pull-downdrive signal from the first pull-up control signal and the firstpull-down control signal; and a first driver configured to generate thefirst data from the first internal data during the read operation andconfigured to generate the first internal data from the second data whenthe first data enablement signal is inputted during the write operation.19. The semiconductor system of claim 18, wherein the first pulsegeneration circuit comprises: a first command decoder configured to besynchronized with the first internal clock signal to generate a firstwrite signal which is enabled when the first internal chip selectionsignal and the first internal command/address signal have a logic levelcombination for performing the write operation and configured to besynchronized with the first internal clock signal to generate a firstread signal which is enabled when the first internal chip selectionsignal and the first internal command/address signal have a logic levelcombination for performing the read operation; and a first flag signalgeneration circuit configured to shift the first write signal based on afirst write latency signal to generate the first write flag signal andconfigured to shift the first read signal based on a first read latencysignal to generate the first read flag signal.
 20. The semiconductorsystem of claim 18, wherein the first I/O control circuit comprises: afirst mode register configured to be synchronized with the firstinternal clock signal to store information on a resistance value of theI/O line, which is inputted through the first internal command/addresssignal, a first target termination signal, a first write latency signal,a first read latency signal, a target termination operation signal and anon-target termination operation signal based on the first internal chipselection signal and the first internal command/address signal during amode register write operation, configured to be synchronized with thefirst internal clock signal to output the resistance value informationof the I/O line as a first pre-pull-up control signal and a firstpre-pull-down control signal based on the first internal chip selectionsignal and the first internal command/address signal during a moderegister read operation, and configured to be synchronized with thefirst internal clock signal to output the stored first targettermination signal, the stored first write latency signal, the storedfirst read latency signal, the stored target termination operationsignal and the stored non-target termination operation signal based onthe first internal chip selection signal and the first internalcommand/address signal during the mode register read operation; and afirst drive control circuit configured to generate the first dataenablement signal from the target termination operation signal and thenon-target termination operation signal when the first write flag signalis inputted to the first drive control circuit and configured togenerate the first pull-up control signal and the first pull-downcontrol signal from the first pre-pull-up control signal and the firstpre-pull-down control signal when the first write flag signal isinputted to the first drive control circuit.
 21. The semiconductorsystem of claim 20, wherein the first drive control circuit comprises: afirst on-die termination (ODT) control circuit configured to generate afirst target write signal and a first non-target write signal which areenabled at a point in time when the first write flag signal is inputtedto the first ODT control circuit based on the target terminationoperation signal and the non-target termination operation signal; afirst enablement signal generation circuit configured to generate thefirst data enablement signal from the first read flag signal during theread operation, configured to output the first target write signal as afirst pre-enablement signal during the write operation, and configuredto inversely buffer the first target write signal to generate the firstdata enablement signal; and a first control signal generation circuitconfigured to generate the first pull-up control signal from the firstpre-pull-up control signal and configured to generate the firstpull-down control signal from the first target termination signal or thefirst pre-pull-down control signal based on the first pre-enablementsignal.
 22. The semiconductor system of claim 18, wherein the firstdrive signal generation circuit comprises: a first pull-up/pull-downsignal generation circuit configured to generate a first pull-up signaland a first pull-down signal, one of which is selectively enabled basedon a logic level of the second data; and a first drive signal outputcircuit configured to generate the first pull-up drive signal and thefirst pull-down drive signal from the first pull-up control signal andthe first pull-down control signal based on the first pull-up signal,the first pull-down signal and the first data enablement signal.
 23. Thesemiconductor system of claim 12, wherein the second semiconductordevice comprises: a second internal I/O circuit configured to besynchronized with the clock signal to generate a second pull-up signaland a second pull-down signal for driving the I/O line with apredetermined drivability based on the second chip selection signal andthe command/address signal during the read operation and the writeoperation; and a second internal termination circuit configured to drivethe I/O line with a drivability adjusted based on the second pull-updrive signal and the second pull-down drive signal during the readoperation and the write operation.
 24. The semiconductor system of claim23, wherein the second internal I/O circuit is configured to storeinformation for driving the I/O line with the predetermined drivabilityduring a mode register write operation; and wherein the second internalI/O circuit is configured to output the information for driving the I/Oline with the predetermined drivability during a mode register readoperation.
 25. The semiconductor system of claim 23, wherein the secondinternal I/O circuit comprises: a second input buffer configured to besynchronized with the clock signal to generate a second internal clocksignal, configured to be synchronized with the clock signal to generatea second internal chip selection signal from the second chip selectionsignal, and configured to be synchronized with the clock signal togenerate a second internal command/address signal from thecommand/address signal; a second pulse generation circuit configured togenerate a second write flag signal which is enabled during the writeoperation based on a logic level combination of the second internal chipselection signal and the second internal command/address signal andconfigured to generate a second read flag signal which is enabled duringthe read operation based on a logic level combination of the secondinternal chip selection signal and the second internal command/addresssignal; a second I/O control circuit configured to generate a secondpull-up control signal and a second pull-down control signal frominformation for driving the I/O line with the predetermined drivabilitybased on the second write flag signal during the write operation andconfigured to generate a second data enablement signal based on thesecond internal command/address signal during the write operation; asecond drive signal generation circuit configured to generate the secondpull-up drive signal and the second pull-down drive signal from thesecond pull-up control signal and the second pull-down control signal;and a second driver configured to generate the second internal data fromthe second data when the second data enablement signal is inputted tothe second driver.
 26. The semiconductor system of claim 25, wherein thesecond pulse generation circuit comprises: a second command decoderconfigured to be synchronized with the second internal clock signal togenerate a second write signal which is enabled when the second internalchip selection signal and the second internal command/address signalhave a logic level combination for performing the write operation andconfigured to be synchronized with the second internal clock signal togenerate a second read signal which is enabled when the second internalchip selection signal and the second internal command/address signalhave a logic level combination for performing the read operation; and asecond flag signal generation circuit configured to shift the secondwrite signal based on a second write latency signal to generate thesecond write flag signal and configured to shift the second read signalbased on a second read latency signal to generate the second read flagsignal.
 27. The semiconductor system of claim 25, wherein the second I/Ocontrol circuit comprises: a second mode register configured to besynchronized with the second internal clock signal to store informationfor driving the I/O line with the predetermined drivability, which isinputted through the second internal command/address signal, anon-target termination signal, a second write latency signal, a secondread latency signal, a target termination operation signal and anon-target termination operation signal based on the second internalchip selection signal and the second internal command/address signalduring a mode register write operation, configured to be synchronizedwith the second internal clock signal to output the information fordriving the I/O line with the predetermined drivability as a secondpre-pull-up control signal and a second pre-pull-down control signalbased on the second internal chip selection signal and the secondinternal command/address signal during a mode register read operation,and configured to be synchronized with the second internal clock signalto output the stored non-target termination signal, the stored secondwrite latency signal, the stored second read latency signal and thestored target termination operation signal based on the second internalchip selection signal and the second internal command/address signalduring the mode register read operation; and a second drive controlcircuit configured to generate the second data enablement signal basedon the non-target termination operation signal when the second writeflag signal is inputted to the second drive control circuit andconfigured to generate the second pull-up control signal and the secondpull-down control signal from the second pre-pull-up control signal andthe second pre-pull-down control signal.
 28. The semiconductor system ofclaim 27, wherein the second drive control circuit comprises: a secondon-die termination (ODT) control circuit configured to generate a secondtarget write signal and a second non-target write signal which areenabled at a point in time when the second write flag signal is inputtedto the second ODT control circuit based on the target terminationoperation signal and the non-target termination operation signal; asecond enablement signal generation circuit configured to output thesecond target write signal as a second pre-enablement signal andconfigured to inversely buffer the second target write signal togenerate the second data enablement signal; and a second control signalgeneration circuit configured to generate the second pull-up controlsignal from the second pre-pull-up control signal and configured tooutput the non-target termination signal as the second pull-down controlsignal based on the second pre-enablement signal.
 29. The semiconductorsystem of claim 25, wherein the second drive signal generation circuitcomprises: a second pull-up/pull-down signal generation circuitconfigured to generate a second pull-up signal and a second pull-downsignal, one of which is selectively enabled based on a logic level ofthe second data; and a second drive signal output circuit configured togenerate the second pull-up drive signal and the second pull-down drivesignal from the second pull-up control signal and the second pull-downcontrol signal based on the second pull-up signal, the second pull-downsignal and the second data enablement signal.